Hmmmm...If I had to venture a guess (based on what happened to the Christian Science movement), I believe the org will eventually contract to about 20% of its current size, and level off there. How long that will take, I have no idea...
They will still have people doing more mindless busy work, but as long as they have some membership, they can claim to be a non-profit religious organization, and if they're smart about their money, won't have to worry about getting tons more from the slashed membership -- just manage their total asset portfolio properly.
Just my theory. I'd be interested in hearing others views on this.